The present invention relates to a system for evacuating a viscous product from within a plastic bag that is constrained by a bin. More specifically, the present invention relates to such a system that includes adjustable scrapers. The adjustable scrapers reduce the risk of harm to the plastic bag and once pumping is complete, ease removal from the plastic bag of the plate carrying the scrapers and the pumps.
Bin unloading systems are customarily used in the food processing and pharmaceutical industries. Viscous products such as tomato paste, icing and medical preparations are provided to manufacturers in bulk in large plastic bags which are placed within bins and subsequently unloaded by floating a platform generally referred to as a follower plate on the surface of the product and pumping the product up through the follower plate.
It is important that the evacuation of the product from the bag be complete to avoid waste. Viscous products often adhere to the bag which may collapse as the product is evacuated to overlie pockets of the product. Since gravity forces the bag to conform to the size of the bin, it is known to attach scrapers to the follower plate which extend laterally into close proximity to the bin supported bag wall to remove product clinging thereto as the product is evacuated.
However, removal of the follower plate from the unloaded bag is often problematical. The bag may collapse over the follower plate and the laterally extending scrapers may damage the bag as the follower plate is withdrawn from the collapsed bag. In addition, the upward scraping of the bag may cause product to be deposited on the top of the follower plate and/or the floor in the area around the bin, requiring cleaning to avoid health hazards and safety issues. Moreover, the product may create a seal between the scrapers and the bin supported bag, and withdrawal of the follower plate may create a vacuum which resists the withdrawal of the follower plate from the bag and/or pulls the bag from the bin as the follower plate is withdrawn.
One known system for bin unloading injects air between the plate and the bag during withdrawal of the plate to keep the bag within the bin. While the injection of air facilitates to some extent the removal of the plate from the bag; it does not address the upward scraping and/or bag damage issues. Moreover, injecting air between the plate often may not be acceptable to the food processors for other reasons.
Another known system utilizes inflatable scrapers to assist in unloading the product from the bag. Accordingly, when the plate is lowered the scrapers are inflated so that they contact the interior walls of the bag. Before the plate is withdrawn the scrapers are deflated so that they are no longer in contact with the bag, preventing the bag from being re-scraped when the plate is removed and eliminating the vacuum created during pumping. Inflated scrapers are generally not rigid enough to adequately scrape the bag and the scrapers themselves may be punctured during the scraping operation resulting in delay and down time for replacement.
Accordingly, it is an object of the present invention to obviate many of the above problems in known systems and to provide a novel system and method for unloading a viscous product contained within a bag constrained by a bin.
One embodiment of the present invention avoids the problems of the known systems by mounting movable scrapers at the edges of the plate selectively extended to remove product adhering to the interior surfaces of the bag when the plate is lowered and retracted out of contact with the interior of the bag upon withdrawal of the plate.
It is another object of the present invention to provide a novel bin unloading apparatus and method that reduces risk of injury to the bag containing a viscous product.
It is yet another object of the present invention to provide a novel bin unloading apparatus and method that eliminates the vacuum created during pumping and eases removal of a follower plate from the bag containing a viscous product.
It is still another object of the present invention to provide a novel bin unloading apparatus and method with scrapers that can be extended or retracted to vary the lateral distance between the scrapers and the bin.
It is a further object of the present invention to provide a novel bin unloading apparatus and method with scrapers that can be extended or retracted to laterally center a follower plate within the bag containing a viscous product that is constrained by a bin.
It is an additional object of the present invention to provide a novel method for maintaining a clean work area when unloading a viscous product from a bag constrained by a bin.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the preferred embodiments.